title: Tunable wetting mechanism of polypyrrole surfaces and low-voltage droplet manipulation via redox.
abstract: This paper presents the experimental results and analyses on a controlled manipulation of liquid droplets upon local reduction and oxidation (redox) of a smart polymer-dodecylbenzenesulfonate doped polypyrrole (PPy(DBS)). The electrochemically tunable wetting property of PPy(DBS) permitted liquid droplet manipulation at very low voltages (-0.9 to 0.6 V). A dichloromethane (DCM) droplet was flattened upon PPy(DBS) reduction. It was found that the surface tension gradient across the droplet contact line induced Marangoni stress, which caused this deformation. Further observation of PPy(DBS)'s color change upon the redox process confirmed that the surface tension gradient was the driving force for the droplet shape change.
authors.affiliation: Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, New Jersey 07030, United States.
authors.forename: Yao-Tsan
authors.initials: YT
authors.lastname: Tsai
authors.forename: Chang-Hwan
authors.initials: CH
authors.lastname: Choi
authors.forename: Ning
authors.initials: N
authors.lastname: Gao
authors.forename: Eui-Hyeok
authors.initials: EH
authors.lastname: Yang
mesh_terms: D004563:Electrochemistry / Q000379:methods; D008752:Methylene Chloride / Q000737:chemistry; D010084:Oxidation-Reduction; D011108:Polymers / Q000737:chemistry*; D011758:Pyrroles / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D011108:Polymers; D011758:Pyrroles; C067635:polypyrrole; D008752:Methylene Chloride